1. Field of the Invention
This invention relates generally to implantable medical device systems and, more particularly, a patient management system to provide an interactive forum for managing patient care, the patient management system to also provide parameter data for treating one or more disorders using an implantable medical device (IMD).
2. Description of the Related Art
Many advancements have been made in treating diseases such as epilepsy. Therapies using electrical signals for treating these diseases have been found to effective. Implantable medical devices have been effectively used to deliver therapeutic stimulation to various portions of the human body (e.g., the vagus nerve) for treating these diseases. As used herein, “stimulation” or “stimulation signal” refers to the application of an electrical, mechanical, magnetic, electro-magnetic, photonic, audio and/or chemical signal to a neural structure in the patient's body. The signal is an exogenous signal that is distinct from the endogenous electrical, mechanical, and chemical activity (e.g., afferent and/or efferent electrical action potentials) generated by the patient's body and environment. In other words, the stimulation signal (whether electrical, mechanical, magnetic, electro-magnetic, photonic, audio or chemical in nature) applied to the nerve in the present invention is a signal applied from an artificial source, e.g., a neurostimulator.
A “therapeutic signal” refers to a stimulation signal delivered to a patient's body with the intent of treating a disorder by providing a modulating effect to neural tissue. The effect of a stimulation signal on neuronal activity is termed “modulation”; however, for simplicity, the terms “stimulating” and “modulating”, and variants thereof, are sometimes used interchangeably herein. In general, however, the delivery of an exogenous signal itself refers to “stimulation” of the neural structure, while the effects of that signal, if any, on the electrical activity of the neural structure are properly referred to as “modulation.” The modulating effect of the stimulation signal upon the neural tissue may be excitatory or inhibitory, and may potentiate acute and/or long-term changes in neuronal activity. For example, the “modulating” effect of the stimulation signal to the neural tissue may comprise one more of the following effects: (a) initiation of an action potential (afferent, and/or efferent action potentials); (b) inhibition or blocking of the conduction of action potentials, whether endogenous or exogenously induced, including hyperpolarizing and/or collision blocking, (c) affecting changes in neurotransmitter/neuromodulator release or uptake, and (d) changes in neuro-plasticity or neurogenesis of brain tissue.
Electrical neurostimulation may be provided by implanting an electrical device underneath the skin of a patient and delivering an electrical signal to a nerve such as a cranial nerve. In one embodiment, the electrical neurostimulation involves sensing or detecting a body parameter, with the electrical signal being delivered in response to the sensed body parameter. This type of stimulation is generally referred to as “active,” “feedback,” or “triggered” stimulation. In another embodiment, the system may operate without sensing or detecting a body parameter once the patient has been diagnosed with a medical condition that may be treated by neurostimulation. In this case, the system may apply a series of electrical pulses to the nerve (e.g., a cranial nerve such as a vagus nerve) periodically, intermittently, or continuously throughout the day, or over another predetermined time interval. This type of stimulation is generally referred to as “passive,” “non-feedback,” or “prophylactic,” stimulation. The electrical signal may be applied by an IMD that is implanted within the patient's body. In another alternative embodiment, the signal may be generated by an external pulse generator outside the patient's body, coupled by an RF or wireless link to an implanted electrode.
Generally, neurostimulation signals that perform neuromodulation are delivered by the implantable medical device via one or more leads. The leads generally terminate at their distal ends in one or more electrodes, and the electrodes in turn are electrically coupled to a tissue in the patient's body. For example, a number of electrodes may be attached to various points of a nerve or other tissue inside a human body for delivery of a neurostimulation signal.
State-of-the-art implantable medical systems utilize an external device to communicate with the IMD for programming the therapeutical electrical signal to be delivered by the implanted device, performing diagnostics and making adjustments to one or more parameters defining the therapeutic electrical signal. A physician may assess the progress of a particular therapy regimen given to a patient during office visits. The physician may examine the patient and make a determination as to the efficacy of the therapy being delivered and may use the external device to reprogram or adjust various stimulation parameters that will modify subsequent therapy delivered to the patient.
There are various problems associated with state-of-the-art implanted neurostimulators. For example, one problem with state-of-the-art implanted neurostimulators is the fact that tedious record-keeping and study of charts are required to perform therapy management to treat patients. When the physician evaluates a patient, various settings for therapy delivered by the IMD are documented in the patient's chart at each visit. At subsequent visits, the physician may then examine previous entries into the chart (e.g., the physician may study the various parameters defining the therapeutic electrical signal, medications taken by the patient, etc.) to make adjustments to the therapy delivered by the IMD. The process of documenting the changes in the parameters, medication and patient evaluation may become quite tedious as well as time-consuming, with a corresponding risk that important information may not be collected or may not be incorporated into the adjustments made to the therapy to improve or maintain efficacy. Further, examining all of the previous chart entries along with the current patient evaluation to determine an appropriate therapy for the patient may become cumbersome or unfeasible, especially where large volumes of data must be collected and correlated. Further, inherent changes or other trends (e.g., progressive changes in a disease symptom) may not be easily detected by the physician upon a review of the various entries in the patient's chart. Therefore, opportunities to improve the efficacy of the therapy may be inadvertently missed due to the tedious nature of patient evaluation and the voluminous data entries made to a patient's chart, as well as to insufficient or improper evaluation of the data collected.
Another problem associated with state-of-the-art IMD systems is the fact that there is a requirement that users (e.g., physicians) independently select various therapy parameters, such as output current and pulse-width, etc., and monitor the effects of the therapy for a particular patient over a period of time. This study of efficacy may reveal some therapy-response data relating to a particular patient. State-of-the-art databases associated with IMD systems generally store data relating to parameters associated with a particular patient in a patient-by-patient basis. However, the industry generally lacks an efficient cross-patient correlation technique to show meaningful relationship between therapy parameters and therapeutic efficacy. Utilizing the data relating to parameters associated with the patient-by-patient analysis described above, physicians must determine various parameters that may be effective for a particular patient. However, one problem associated with this technique is the fact that a set of parameters that is effective for one patient may not be ideal for another patient. The state-of-the-art generally lacks a method of performing an evaluation of favorable therapy parameters that may be employed for a particular type of patient. This may prompt the requirement of several iterations in a trial-and-error type of estimation process for determining appropriate parameters for achieving desirable efficacy and results when treating a patient.
The present invention is directed to overcoming, or at least reducing, the effects of one or more of the problems set forth above.